Blame the
Celts.
The idea behind the bard is similar to the idea behind the wizard - someone whose special knowledge makes them able to access magic. The wizard archetype is bound to the book - to literacy, to runes, to heiroglyphs, to sacred writing. It is about the knowledge that being able to
read and write could unlock.
The bard is the same idea, but from pre-literate societies. That's why the song routine - epic poetry and divine music and a keen memory for stories. Without writing, you turn to the bard to hold your histories, to tell your most important stories, to recite your sagas and your lineages. Song happens to be the way most people remembered things before writing was invented, because singing something makes it easier to remember.
This gave those who could sing these songs power - they could conjure the dead, awaken the gods, stir emotions in stoics, call up memories long-forgotten....
magic. Their power is akin to the power of media - they say something, and thus it becomes true to an extent, people listen to what they have to say.
Bardic archetypes for me are typically those legendary speakers - your celtic bard, your Nordic skald, your Arabic sha'ir, your Orpheus, your Apollo, whatnot. There's not a lot of those in pop media, but we're a literate society, so of course there wouldn't be. It's not as valued and important a skill today.